Apparently a few retards have been whinging on the forums [why is this remarkable again?] that Blizzard is blatantly Horde-biased, based on the fact that one of the most significant lore characters at the moment used to be leader of the Horde, and some other miscellaneous rumours presented as fact. They must have been whinging quite a bit because Blizzard went to the trouble of getting Dave Kosak to write an explanation which boils down to "What? Do you people even understand the concept of drama?"
Wasn't the entire last expansion centred completely around a character who was a previously a major Alliance lore figure? Where was the complaining about bias then? Not to mention the prominence of Tirion Fordring and Bolvar Fordragon in that storyline, both Humans, one explicitly from the Alliance faction.
Personally, I think this is all about racism. People just aren't ready for an Orc to be their saviour.